Annual report pursuant to Section 13 and 15(d)

INCOME TAXES - Schedule of Effective Rate Reconciliation (Details)

v3.20.4
INCOME TAXES - Schedule of Effective Rate Reconciliation (Details) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Effective Income Tax Rate Reconciliation, Amount [Abstract]      
Effective Income Tax Rate Reconciliation at Federal Statutory Income Tax Rate, Amount $ (41) $ 66 $ 119
Income Tax Reconciliation Tax Deduction for percentage depletion in excess of cost depletion (42) (49) (55)
Effective Income Tax Rate Reconciliation, Noncontrolling Interest Income (Loss), Amount (9) 0 0
Effective Income Tax Rate Reconciliation, Disposition of Business, Amount 0 846 162
Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Amount (11) 0 0
Effective Income Tax Rate Reconciliation, Other Adjustments, Amount (8) 1 2
Income Tax Expense (Benefit) $ (111) $ 18 $ (475)
Effective Income Tax Rate Reconciliation, Percent [Abstract]      
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent 21.00% 21.00% 21.00%
Income Tax Reconciliation Tax Deduction for percentage depletion in excess of cost depletion percent 22.00% (16.00%) (10.00%)
Effective Income Tax Rate Reconciliation, Noncontrolling Interest Income (Loss), Percent 4.00% 0.00% 0.00%
Effective Income Tax Rate Reconciliation, Disposition of Business, Percent 0.00% 271.00% 29.00%
Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Percent 6.00% 0.00% 0.00%
Effective Income Tax Rate Reconciliation, Other Adjustments, Percent 4.00% 1.00% 0.00%
Effective Income Tax Rate Reconciliation, Percent 57.00% 6.00% (84.00%)
Current year activity [Member]      
Effective Income Tax Rate Reconciliation, Amount [Abstract]      
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Amount $ 0 $ 0 $ (80)
Effective Income Tax Rate Reconciliation, Percent [Abstract]      
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Percent 0.00% 0.00% (14.00%)
valuation allowance reversal [Member]      
Effective Income Tax Rate Reconciliation, Amount [Abstract]      
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Amount $ 0 $ 0 $ (461)
Effective Income Tax Rate Reconciliation, Percent [Abstract]      
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Percent 0.00% 0.00% (81.00%)
Dissolution of entities [Member]      
Effective Income Tax Rate Reconciliation, Amount [Abstract]      
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Amount $ 0 $ (846) $ (162)
Effective Income Tax Rate Reconciliation, Percent [Abstract]      
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Percent 0.00% (271.00%) (29.00%)